linux-kernel - Re: [PATCH] sched: mark parent and real_parent as _

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 15 Dec 2011 08:20:59 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Kees Cook <keescook@...omium.org>
Cc:	linux-kernel@...r.kernel.org,
	Peter Zijlstra <peterz@...radead.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH] sched: mark parent and real_parent as __rcu


* Kees Cook <keescook@...omium.org> wrote:

> On Wed, Dec 14, 2011 at 11:08 PM, Ingo Molnar <mingo@...e.hu> wrote:
> > * Kees Cook <keescook@...omium.org> wrote:
> >
> >> The parent and real_parent pointers should be considered __rcu, since
> >> they should be held under either tasklist_lock or rcu_read_lock.
> >>
> >> Signed-off-by: Kees Cook <keescook@...omium.org>
> >> ---
> >>  include/linux/sched.h |    4 ++--
> >>  1 files changed, 2 insertions(+), 2 deletions(-)
> >
> > Did you get some warning that alerted you to this problem? If
> > yes then please include it in the changelog, so that people
> > hitting the message can easily find it.
> >
> > Same consideration applies the second patch as well.
> 
> No, this was via code inspection related to reviews of the 
> Yama LSM's use of these structures and comparing the RCU and 
> tasklist_lock behavior/requirements seen in the rest of the 
> kernel. Most attempts at using sparse after this change were 
> not very successful due to the high volume of unrelated noise 
> currently seen with "make C=2", but I was able to confirm that 
> the apparmor and tomoyo patches were flagged by sparse, at 
> least. When this __rcu marking is in place, if there is a 
> place that might need rcu_dereference, it would show up as 
> "warning: dereference of noderef expression".

ok - i'll apply the first patch, please send the second one 
against -tip, it does not apply anymore. (scheduler got moved to 
kernel/sched/)

Thanks,

	Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/